Space telegraphy.



No. 884,076. PATENTED APR. '7, 1908. E. R. CRAM.

SPACE TELECRAPHY.

APPLICATION FILED MAY 7, 1906.

narran sacara carenze ERNEST R. CRAM, 0F CAMBRIDGE, MASSACHUSETTS, ASSIGNOR'TO STONE TELEGRAPH AND TELEPHONE COMPANY, OF BOSTON, MASSACHUSETTS.

SPACE TELEGRAP'.

no. escote.

To all whom -itmay concern:

Be it known that l, ERNEsr R. CRAM, a ,Citizen of the United States, and a resident of Cambridge, in the county of Middlesex and State of Massachusetts, have invented a new and useful improvementy in Space Telegraphy,l of which the following is a speciiication.

My invention relates to the art of transmitting intelligence from one station to another by means of electroma netic wavesv without the use of wires to gui e the waves to theirdestination; and it relates more particularly to systems for receiving signals transmitted bysuch waves.

The object of my invention is toso adjust the4 circuits of a space telegraph receiving system that a persistent train of lelectromagnetic waves of the frequency to which an associated resonant receiving circuit is attuned impinging upon the elevated conductor shall cause said resonant receiving circuit to respond energetically While persistent trains of electromagnetic Waves of frequencies dierent from that to which said resonant -circuit is attuned shall produce no appreciable response in lsaid resonant circuit, and abrupt or impulsiveelectrical forces acting upon the elevated conductor shall in like manner produce practically no appreciable response in said resonant circuit. y

l accomplish the object of my invention by interposingbetween the elevated receiving conductor system and the resonant receivin circuit a circuit which is tightly coupled to sai elevated conductor systernyand which has a pronounced natural rate of vibration different from that of said resonant receiving circuit, but which is highly responsiveI to ersistent trains of electrical oscillat-ions o the frequency to which said resonan't receiving circuit is attunedf ln other words, l accomplish the object of the present invention by giving the aforesaid interposed circuit a pronounced natural rate of vibration diii'erent from that of the Waves the energ of which is 'to be received and, consequent different from that to which the associated resonant receiving circuit'is attuned, and by making said interposed circuit highly responsive to persistent trains of waves raving the frequency of those the energ of which is t0 be received and, consequent y, having the frequency to which the associated resonant receiving circuit is attuned.

specification of Letters recent.

Application filed May T, 1906. Serial N. 335,519.

Patented April 7, '190%'.

The invention may best be understood by havingreference to the drawings which accompany yand form a part of this specifica-- tion, and which illustrate conventionally several organizations of circuits and apparatus whereby the liereinbefore stated Iobjects may.

conveniently be realized in prac-tice.v

in the drawings, Figure l represents a space telegraph receiving system in which a circuit which is highly responsive to persistent trains of electrical oscillations of deiinite frequency, but which has a pronounced natu ral rate of vibration different from said free quency, is tightly coupled to an elevated receiving conductor system and is interposedk between said system and a resonant receiving nite fre uency. Fig. 2 represents a modification o the system shown in Fig. Lin which the interpose ductor system.' Fig. 3 represents a further circuit is conductively tightlyV coupled with the elevated receiving con--v 7 0 circuit which is attuned to the aforesaid den? Y modification of the system shown in nFig. l in which :the .coupling between the aforesaid in -terposed circuit and the resonant circuit is an electric couplin in the iigures, T is an elevated receiving `The various elements above enumerated are distinguished fromv each other as to pos1.

tion and function by providing the reference letters with exponents andsuliscripts.

A represents a circuit tightly coupled to the elevated receiving conductor system andv including a parallel Vbranch circuit con. taining capacity in one branch and inductance in the otherbrancinjy D represents a resonantgreceivlng circuit and D represents a resonant; weeding-,outs

circuit, eac of said-circuits being attunedf-to the frequency of the Waves the energy of.

which is to be received.

For a more completeexposition'ofA the gen-v eral principles involved lin preventing theresponse of a `resonant receiving circult. to the electrical oscillations developed 'by abrupt or impulsive electrical forces .acting upon an elevated receiving conductor system, with which'said resonant 'receiving circuit is` as sociated, byv giving the elevated receiving conductor system natural rates of vibration different from the frequency to which said resonant receiving circuit is attuned, or by givinit a pronounced natural rate of vibration i ciated resonant receiving circuit is attuned, while making it'highly responsive to persistenttrains of waves of the frequency to which the associated resonant receiving cirinductance and yca acity, and is tightl coupled in any suita le manner with the elevated conductor system. On account of the aforesaid ltight coupling. lthe elevated conductor s stem and the circuit A constitute ractica y one oscillating system containing istributed inductance and distributed caacity aswell as lumped inductanceY and umped capacity. This system so constituted will have a ronounced natural' rate of vibration which isdierent from the frequencyf to which the circuits D and D are attuned, and for persistent trains of electrical oscillations of the 'frequency to which the vcircuits D land D are attuned the reactance of the parallel lbranch 'circuit B balances the reactance of the circuit A as affected by its association -wi'th the elevated conduct-or system. AAccording'rlly when abrupt or imulsive'forces act upon the elevated con-v uc'torV, the currents developed in the cir cuit A, are of such fre uency or frequencies resonant receiving fsisten'tly applied tuned act upon the elevate lthe frequency to whic the resonant receivas topiOduce practica y no response in the circuit, while when perorces of the frequency to which said resonant receivindg circuit is atthe currents 'developed in the circuit A are ofrelatively large amplitude and, being of ing circuit is att'une'd, are translated to said resonantreceivin'gcircuit.

When tbef'requency of the waves the energy of which is to be received is lower 'than that natural lto vthe circuit B when isolated, the amplitude of the current flowing through the inductance branchy of circult B is greater than that flowing through fferent Afrom that to which theasso-v beihad toV yassociated with said condenser branch, al-

conductor V,

such case, as shown in igs. 1 and 2, the

resonant weeding-out circuit D may be associated with the inductance branch of circuit B. When the frequency `of the waves the energy of which'is to be received is higher than that natural to the circuit B when i'solated, the amplitude of the current flowing through the condenserbranch of circuit B is greater than that flowing through the inductance branch thereof. Accordingly in such case the resonant weeding-out circuit may be thou h for' convenience in controlling the coup ing between circuits B and D the circuit D may be associated'with the coil of circuit Al or the coil of circuit B.' The coupling between circuits B and D and circuitsl D and D, as well as the coupling between circuitsB and A and circuits B and D preferably is a loose coupling and may be accomplished in any yof the ways set forth at length in Patent No. 767,984. 3

The circuit Al in Fig. 3 does notI contain an elastic element, so that'the variation with frequency of the reactance of circuit A1 when isolated is linear, but in virtue of the tight coupling between said circuit` and the ele- `vated conductor system V1`E, the reactance frequenc variation of the system consisting of said e evated conductor system and said circuit A, will be re resented by a discontinuous curve'somew at similar to curve (1L) shown in'Fig. 2 of. Patent No. 802,425 or in Fig. 21 oflatentNo. 767,994, above' re-v ferred to. The circuits A of Figs. l and 2 each contains 'a condenser C" and the frequency-reactance variation ofeach when iso` lated will be that characteristic of a resonant circuit, butin virtue of the tight coupling between each said circuit and its elevated conductor system, thereactance-frequency variation of the system consisting of each elevated conductor system andv its associated circuit A will berepresented by a discontinuous curve somewhat similar to that above referred to, of Fig. 2 of Patent No. 802,425. ln all figures the rea'ctan'ce-frequenc variation of thecircuit B when isolated wi l be represented by a discontinuous `curve similar to the curve (3) shown in Fig. 2 of Patent N o. 802,425 or ysimilar to the curve shown in Fi 23A of Pat-ent "No 757,994. According y without going into a incre-detailed ex lanation, it 'willbe seen that in each case t e reactance of the elevated conductor system 'and its associated ti htlyfcoupled circuit A or A will be balanced ythe reactance of the parallel branch circuit for a ersistent train of electrical oscillations o definite freuency, while for abru t or im ulsive forces t e pronounced natura rate o vibration ofl each elevated conductor system and. its assoing thepara lel branch circuit B will be different from that of the resonant receiving circuit. 'y

In the system shown in Fig. 2' the circuit A containing the parallel branch circuit B is interppsed between the resonant receiving circuit @and the system AB. e For a persistent train of electrical oscillations of' the frequency to Which the resonant receiving circuit D is attuned, the reactance of circuit B is equal and o posite to the reactance Tof the circuit A so t at the system A B will be highly res onsive' to persistent trains of electrlcal osc' ations of said frequency, while for abrupt or impulsive electrical forces acting upon the circuit A', the natural rate of vibration lof the system A B" will be diiierent from that, to which the circuit Dis attuned.l

It Will be obvious that many modifications maybe niadein the circuit arran ements hereinbefore specifically described Ior the purpose of more fully disclosing my invention and that therefore I do not wish -to be limited to any of the specic arrangements of circuits and apparatus 'set forth herein. I

I claim, 1. In a s ace telegraphreceiving system, an elevatedp receiving conductor system; a resonant receiving circuit attuned'to the frequency of the waves the energy ofwhich is to be received; and a circuit tightly coupled to said elevated conductor system vand interposed between said elevated conducto'r system and said resonant receiving circuit, said circuit having a pronounced natural rate'fof,`

vibration dierent from that of said resonant receivmg circuit. p

2. In a s ace telegraph receiving system,

. an elevate receiving conductor system; a

n resonant receiving circuit attuned to the frequency of the waves the energy of which is to be received; and a circuit tightly coupled to said elevated conductor system and interposed between said elevaed conductor system and said resonant rec iving circuit, said circuit being provided with means whereby it is given a pronounced natural rate of vibration different from that of the resonant receiving circuit and whereby, for a persistent train of electrical oscillations of the frequency to which said resonant receiving cirvvated conductor system.

cuit is attuned, the reactance of such inter- L posed circuit is rendered zero. u A

3. In a spa'ce telegraph recelving system, an elevate quency of the waves the energy of which is to be received; and a series of circuits, interposed between said elevated receiving conuctor system and said resonant receivin circuit and each havingl a pronounced natura rate of vibration diierent from that of said resonant receiving circuit, the first circuit of said series being tightly coupled to said ele- 4. In a` space telegraph receiving system, an elevated receiving conductor system; a 'resonant receiving circuit attuned to the frequency ofthe waves the energy of which is to be received; and a series 'of circuits, interv receiving conductor system; a resonant receiving circult attuned to the freposed between said elevated receiving conductor system and said resonant/receiving circuit and each provided With means whereby itis given a pronounced natural rate of vlbration different from that of the resonant yreceiving circuit and whereby, for a persistent train of electrical oscillations of the frequency to whichsaid'resonant receiving circuit is attuned, the reactance of each of such interposed-circuits'is rendered zero, the first circuit of said series-being tightly coupled to saidelevated conductor system.

5. In a' space telegraph receiving system, an`eleva'te receiving conductor system; a resonant receiving circuit attuned to the frequency of the ,waves the energy of which is to be received; a circuit. tightly4 coupled to the said elevated conductor system and interposed between said elevated conductor system and said resonant receiving circuit; and means iving such inter osedl circuit a pronounce natural rate ofp vibration different from that of said resonant receiving circuit and making it highly res onsive to ersistent trains of electrical osci lations o quency to which said resonant receiving circuit is attuned.

In testimony whereof, Il have hereunto Gno. K.' WooDwoRTn, E. B. ToMLINsoN.

the frey 

